Fix #6752 preserve shared entity on subgraph transport failure

[michaelstaib]

Overview

Fixes #6752

This change addresses shared top-level entity lookups when one subgraph fails with a transport error.

What changed

• Added a regression test (Issue6752Tests) that reproduces a shared productById query where one subgraph is offline and verifies:
  • data.productById stays an object
  • fields from the failing subgraph are null
  • fields from the healthy subgraph are still returned
• Updated Fusion planner lookup argument handling for shared root lookups:
  • Reuses root field arguments directly from the original operation when available.
  • Avoids creating unnecessary lookup requirements/dependencies for that case.
  • Normalizes source extraction to root for this no-requirements lookup path.
• Updated value completion for object fields to rehydrate null targets when later shared-source object data arrives.

Test commands

• dotnet test src/HotChocolate/Fusion-vnext/test/Fusion.AspNetCore.Tests/HotChocolate.Fusion.AspNetCore.Tests.csproj --filter "FullyQualifiedName~Issue6752Tests"

  • Passed on net8.0, net9.0, net10.0.

• dotnet test src/HotChocolate/Fusion-vnext/test/Fusion.AspNetCore.Tests/HotChocolate.Fusion.AspNetCore.Tests.csproj --filter "FullyQualifiedName~Issue6752Tests|FullyQualifiedName~SourceSchema_Request_Fails_For_Lookup"

  • Passed on net8.0, net9.0, net10.0.

[github-actions]

Fusion Gateway Performance Results

Simple Composite Query

	Req/s	Err%
Constant 2 (50 VUs)	3330.56	0.00%
Ramping 2 (0-500-0 VUs)	3831.39	0.00%

Response Times

	Min	Med	Avg	P90	P95	Max
Constant 2	1.06ms	12.12ms	14.74ms	23.73ms	33.15ms	263.84ms
Ramping 2	1.13ms	52.42ms	57.25ms	100.28ms	142.73ms	287.36ms

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Deep Recursion Query

	Req/s	Err%
Constant 2 (50 VUs)	791.10	0.00%
Ramping 2 (0-500-0 VUs)	939.19	0.00%

Response Times

	Min	Med	Avg	P90	P95	Max
Constant 2	10.64ms	55.06ms	61.01ms	78.20ms	95.15ms	647.32ms
Ramping 2	3.10ms	202.97ms	219.67ms	449.92ms	501.75ms	835.96ms

---

Variable Batching Throughput

	Req/s	Err%
Constant 2 (50 VUs)	5696.17	0.00%
Ramping 2 (0-500-0 VUs)	5235.88	0.00%

Response Times

	Min	Med	Avg	P90	P95	Max
Constant 2	0.17ms	8.20ms	8.67ms	14.52ms	17.51ms	104.38ms
Ramping 2	0.18ms	39.18ms	43.86ms	81.52ms	107.85ms	225.02ms

---

Runner 2 = benchmarking-2

Run 22495058103 • Commit 4b661fb • Fri, 27 Feb 2026 16:50:49 GMT